1. Field Of The Invention
The present invention relates to a high impact polyamide composition. More particularly, the present invention is concerned with a polyamide composition comprising at least one polyamide having a specific relative viscosity in sulfuric acid, at least one ethylene ionomer resin and at least one monoepoxy or carbonate compound. The polyamide composition may further comprise an elastomeric olefin copolymer, an elastomeric styrene copolymer, and/or a polyvalent alcohol. The polyamide composition has excellent mechanical strength and thermal resistance properties so that it can advantageously be employed in the manufacture of various automobile parts and sporting goods. The polyamide composition also has excellent impact strength, especially excellent weld-line impact strength.
2. Discussion Of Related Art
Heretofore, various polyamide compositions having improved impact strength have been proposed. For example, these include a polyamide composition comprising a polyamide and, blended therewith, an ethylene ionomer resin (see, for example, U.S. Pat. No. 3,845,163 and Japanese Patent Application Publication Specification No. 54-4743/1979), and a polyamide composition comprising a polyamide and, blended therewith, an ionomer resin or an elastomer having a low tensile elasticity and having a specific polar group, capable of bonding with the polyamide, wherein particles of the ionomer resin or elastomer having a diameter of about 1 .mu.m or less are dispersed in the polyamide (see, for example, U.S. Pat. No. 4,174,358. Moreover, the known polyamide compositions include a polyamide composition comprising a polyamide and, blended therewith, an ionomer resin and a monoepoxy or carbonate compound (see, for example, U.S. Pat. No. 4,086,295, and a polyamide composition comprising a polyamide and, blended therewith, an ionomer and an elastomeric olefin copolymer (see, for example, U.S. Pat. No. 4,485,214.
All of the above-mentioned known polyamide compositions, however, have a drawback in that although shaped articles made therefrom exhibit improved impact strength at their portions other than the weld-line portions, they are not always good with respect to impact strength at their weld-line portions and the average of the impact strengths at their weld-line portions is low. Weld-lines are the lines or surfaces along which a polymer must reunite and adhere to itself after flowing around an interference during molding. In the manufacture of a shaped article from polyamide compositions, the shaped articles, except those having an extremely simple configuration, are generally caused to have one or more weld-lines. If the shaped articles are poor with respect to the impact strength at their weld-line portions, they have difficulties in practical use.